3B55.10 Speaker Beats and Interference

Concepts

Interference and diffraction of sound

Overview

A function generator drives two stationary speakers placed in front of the class. The students cover one ear and slowly move their heads around to hear the interference pattern.

Details

Equipment

  • [1] Function generator
  • [2] Speaker

Classroom Assembly

  1. Turn on the function generator.
  2. Set the amplitude to a minimum.
  3. Set the function generator to produce a 300 Hz sine wave.
  4. Place the two speakers about 2m apart.
  5. Connect a function generator to both speakers.
  6. Slowly increase the amplitude.

Important Notes

  • In large classrooms, the approximate distance the students' head must move to go from high amplitude to low amplitude is longer.

Script

  1. Instruct the students to plug one ear and move their heads from side to side.
  2. Have the students approximate the distance between region of high amplitude and low amplitude.

 

Additional Resources

References

  • PIRA 3B55.10

Disclaimer

  • Don't attempt this at home!

Last revised

  • 2018

Technicals

Related AV

Related demos

 

If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.